INCOME TAX RETURN FILING FOR TRUST REG

I am running a charitable trust purely for charitable purposes such as Education,medical relief,relief to the poor etc.The trust is registered u/s 12A of the income tax act 1961.The source of income of the trust is Bank interest for FD only.The trust has invested it's corpus fund as per section11(5) of the act and No 80G exemption.The trust's annual income is 1.75 Lakhs which is below the threshold exemption limit.I need your advice regarding filing ITR 7.As the income is below Rs.2.50 Lakhs is it mandatory for the trust to file its return of income in ITR 7 under section 139 when there is no TDS.Please Guide me.